The Prohibition era in America, which lasted for well over a decade and—inconceivable as it might be today—effectively banned the sale and production of booze in the United States, ended with the ratification of the 21st Amendment on Dec. 5, 1933.

The first Boston Marathon bomb exploded about two hours and forty minutes after the winner of the men’s race had crossed the finish line on Boylston Street. I was standing on the finish line photographing runners; some dressed in costumes, others were holding the hands of children and family members as they shared the joy of finishing together.

The first bomb went off on the Boylston Street sidewalk less than 45 feet from me. The percussion from the blast jolted me. I saw runner Bill Iffrig from Lake Stevens, Wash., fall to the pavement. I ran forward to photograph him. Three Boston Police officers bolted towards him at the same time, one with her gun drawn, as the second bomb exploded three blocks away. I had not seen the officer's gun until I edited the photos. I didn’t understand at first what had happened, thinking maybe it was a cannon salute or a manhole explosion. But when I ran to the sidewalk area several feet away, I saw the horror of what the bomb did. I then began to comprehend what I was photographing. I tried not to take my eye off the camera. Smoke was thick. A police officer looked me in the eyes and said, “You shouldn’t be here. Another bomb could go off.” Bodies were still smoldering, legs were blown off, and massive amounts of blood covered the sidewalk.

I photographed Kevin Corcoran from Lowell using his belt to stop the flow of blood from his wife Celeste’s mangled leg. I photographed Celeste’s daughter, Sydney, lying on the ground as two men wrapped t-shirts on her legs. Nicole Gross from Charlotte, North Carolina, struggled to get up, her shirt in tatters, her leg severely injured. A pool of blood surrounded her. A police officer reached over and placed two fingers on Krystal Campbell's neck, looking for a pulse. Krystal had passed away. Celeste lost both legs. Sydney lost nearly all her blood from a cellphone-size piece of shrapnel that lodged in her thigh and severed her femoral artery. I continued taking photos for about 12 minutes. Then I got my laptop, which was still plugged in near the finish line, and walked to my car and drove to the Globe office. I took off my shoes, which were covered with blood, and began to edit my photos. On bad nights, the images still play over and over in my mind.

More than ever, photography has become the predominant means for us to communicate. An absolutely astounding number of pictures are shared every single day — half a billion, and rising. And yet somehow, even amid this colossal torrent of imagery, the best pictures rise to the top.

Our top ten photographs of 2013 celebrate a variety of images from a multitude of photographers, including seasoned photojournalists Tyler Hicks (the Westgate Mall Massacre in Nairobi), Philippe Lopez, (Super Typhoon Haiyan’s destructive wrath upon the Philippines), and John Tlumacki, for his extraordinary coverage of the terror bombing at the Boston Marathon.

The news has introduced to us several emerging photographers this year, including Mosa’ab Elshamy who documented the bloody demonstrations in Cairo’s Rabaa Square, and Daniel Etter, who made an iconic photograph during the Turkish uprising. In late April, activist and photographer Taslima Akhter made the single most haunting photograph of the fire that killed more than 1000 in a Bangladeshi garment factory: a final embrace. Although she has spent months trying to learn the names of the victims shown in that unsettling, moving picture, Akhter has been unable to identify them.

In September, TIME published a set of images recording a brutal execution in Syria; at the time, we withheld the photographer’s name for security reasons. Now, he has decided to come forward for the first time. He is Emin Özmen, a Turkish photographer awarded a World Press Photo prize in 2012 for his images of torture in Aleppo. The execution pictures he made over the course of one day in the midst of the Syrian cataclysm bear witness to that war’s unspeakable, and ongoing, atrocities.

Photographer Peter van Agtmael has spent many years documenting the wars in Iraq and Afghanistan and their aftermath. In June, he made a touching portrait of an Iraqi war veteran-turned stand-up comedian, Bobby Henline, as part of a photo essay and documentary film for TIME.

David Jenkins captures an astounding photograph of a great white shark near Seal Island, South Africa whose prey, the great fur seal, looks to have gotten away. You’ll have to read his account to find out.

Early in the year, Tim Holmes, his wife and five grandchildren took refuge in the sea bordering their property when a wild brush fire swept through their Australian coastal town. Holmes took a harrowing picture with his mobile phone to send to his daughter as proof that they were all okay. While Holmes is not a news photographer, his picture is testament to the power of the mobile phone and the fact that some of the most newsworthy and emotional pictures can be made by normal citizens in the midst of a breaking story.

We spoke to each of the 10 photographers about the image that he or she shot; their words provide the captions accompanying the photos in the gallery above.

In the next few weeks, TIME.com will roll out our year-end photo specials. For the third year in a row, we’ll present our annual “365: Year in Pictures” gallery — a comprehensive look at the strongest picture from each and every day of 2013; the Most Surprising Pictures of the Year; TIME’s best photojournalism and portraiture from 2013 and TIME’s choice for the Wire Photographer of the Year. TIME’s Senior Photo Editor, Phil Bicker, is curating many of these galleries with help from the photo team at TIME. Bicker’s discerning and nuanced eye is responsible for the curation of TIME’s Pictures of the Week — galleries that present surprising and occasionally offbeat photographs from around the globe. We hope you will enjoy the selections and keep watching for updates through the end of 2013. Think we missed something? Tell us your favorite photo of 2013 using #TIME2013.

Finally, I’m especially proud to announce that our upcoming Dec. 23rd issue of TIME will be dedicated fully to the art and power of the photograph in 2013. Stay tuned…

Kira Pollack is TIME’s Director of Photography. Follow her on Twitter @kirapollack.